Loud-speaker



June 10, 1930 i M.- c. HOPKINS 1,763,048

I LOUD SPEAKER Filed Dec. 22., 1925 5 Sheets-Sheet 1 June 10, 1930. M. c. HOPKINS 1,753,048

LOUD SPEAKER Filed Dec. 22, 1925 3'S heets-Sheet 2" I v I gmmtm attain, s

June 10,1930. M. c. HOPKINS 1,763,048

LOUD SPE KER Filed Dec. 22, 1925 "s Sheets-Sheet 5 I dbm Patented June 10, 1930 UNITED ,STATES' PATENT OFFICE MARCUS C. HOPKINS, OF WASHINGTON, DISTRICT COLUMBIA, ASSIGNOR TO .110?- runs CORPORATION, or JERSEY CITY, wan.

NEW JERSEY, A CORPORATION OF DELA- LOUD-SPEAKER Application filed December 22, 1925. Serial No. 77,083.

The present invention relates to loud speakers suitable for use with radio receiving sets,

or as announcers for telephone and like wired circuits. The principal object of the invention is to provide a highly efficient loud speaker, capable of regenerating or reproducing sound waves directly in free air, without distortion as in a horn or other amplifying device, the sound so regenerated retaining substantially, the same balance of high and low tones as the. original sound from which the actuating force .was derived.

To this end the improved loud speaker comprises a relatively light and stiff diaphragm or tympanum, preferably conical in shape, and a sound boar or resonator having greater mass than that of the diaphragm. The connection between the diaphragmand the resonator or sound/board is such that the diaphragm will res nd the relatively hlfih fre uencies and wi 'e ficiently reproduct e hig tones or sounds," the relatively low frequencies will bettalnsniitted through sa d connection to the soundboard so that 1t will respond tothe relatively low frequencies and willeflici'ently reproduce them. Several forms of loud speakers constru in accordance'withthe invention are d sclosed in the accompanyingdraw' ,inwhich:

concert halls andsimilar volume of sound is desire Fig. 2 is a side elevation of the speaker the grain of the inner ply running transverse showninFig.1';

Fig. 3. is a rear view of the loud speaker shown in Fig. 1;

Fig.4 is a vertical section taken on the line 4.4 of Fig. 3-;

Fig. 5 is an enlarged detail vertical section of the central of theJoud speaker showin the connection between the dia{ h iriayfi a 'nisr'n-housed in the-casing 7. The casing 7 i may be attached to a support or spider 8 phragm and the sound board;

Fig. 6 is a front elevation of another type same prinei of loud speaker operatingon the ple as that shown in Fig. 1; I Fig. .7 is a top plan viewof the. loud speaker shown in Fig. 6;

Fig. 8 is a rear elevation of the speaker shown in Fig.6;

Fig. 1 is a frontview o a loud speaker: especially designed for use in hotels, theatres,

where a large Fig. 9 is a vertical section taken on the line 99 of Fig. 8. y

Referring first to Figs. 1 to 5 inclusive, the loud speaker shown in these figures comprises a central conical-diaphragm or tympanum 1 coupled to a vibrator external annular resonator or sound boar 2 by means of a semiflexible coupling, shown in Fig. 5. The conical diaphragm 1 is preferably made of cover paper out and folded to shape and glued along a radial seam. Near the outer edge of the cone thus formed the paper is creased and then folded up to form a forwardly flaring brim 3 (Fig. 5). This brim naturally assumes an angle to the plane of the base equal that a part of the brim be left free to form a hinge on which the cone may float. Thus wit a brim wide the cemented portion 5 may have a width of of an inch more or less and the remainder of the brim may be 80 left free to swing.

The resonator or sound board 2 is preferably made of wood. It can conveniently be made of 3-ply veneer as shown in Fig. 5 with to the grain of the two outer plies. Fir and spruce may be used for this purpose with good results.

The vibrator actuating force'is applied. to the apex o the conical diaphragm by means of a rod or wire 5 which is adapted to be maintained in fixed relation with the diaby means of a set screw 6. The rod 5 actuated by electromagnetic mechawhich in turn may be affixed to the resonator or sound board by means of wood screws 9. While the loud speaker shown inFigs. 1

to 5 inclusive may be made of any desired size within reasonable limits, it has been found that for concert work excellent results have been obtained bymaking the conical diaphragm approximately 1? inches in outside diameter and theresonator or sound board approximately 4 feet in outside diameter. The relatively large size of the loud speaker shown in Figs. 1 to 5 inclusive makes it desirable to suspend it by cords or chains which may be attached to any suitable part of the loud speaker, preferably the spider 8. The loud speaker may be suspended from the cealing of a room, a bracket or any other supnorting device.

The loud speaker shown in Figs. 6 to 9 inclusive is very similar in construction to that above described as it' comprises a conical tympanum 1. a sounding board or resonator 2, a spider 8 for supporting the casing 7 of the electromagnetic actuating mechanism, and a forwardly flaring brim 3 on the cone which is attached to the inner edge of the sound board in the same manner as explained in connection with Figs. 1 to 5. The main difference between the speaker shown in Figs. 6 to 9 inclusive and that shown in the first five figures is that the sound board or resonator 2 is of smaller diameter than the sound board shown in the first five figures. The conical diaphragm 1' mayor may not be smaller than the conical diaphragm of the loud speaker of Figures 1 to 5. The reduction in overall size of the loud speaker shown in Figs. 6 to 9 inclusive makes it possible to support the speaker on a table or other horizontal surface and for this reason the sound board 2 is provided with suitable legs or cross pieces 10 glued or otherwise fastened to the sound board. The sound board may be provided with an opening 11 to provide a hand grip for moving the loud speaker from one place to another. In constructing a loud speaker of the type shown in F 6 to 9 I have found that excellent results are obtained by making the cone 2 approximately 15 in diameter and the sound board ap 'n'oximately 22 in diameter. This makes the transverse width of the annular sound board approximately 3 but good results may be obtained by making the sound board of even less width than this or of even greater width than the sound board shown in Figs. 1 to 5 inclusive.

In both types of the speaker the conical diaphragm etliciently reproduces the higher tones and perhaps some of the intermediate tones while the resonator or sound board efliciently reproduces the lower or bass notes. It will therefore be seen that the character of the flexible coupling between the conical diaphragm and the sound board is important as it should be flexible enough to permit the conical diaphragm to respond to the higher frequencies and it should be rigid enough to transmit the lower frequencies to the sound board.

In a loud speaker constructed in accordance with the foregoing description, the regenerated or reproduced sound waves are substantially directly proportional both quantitatively and qualitatively to the actuating force and the sound so reproduced retains substantially the same balance of high and low tones as the original sound from which the actuating force was derived.

I claim: 1

1. A loud speaker comprising a central relatively light and stiff diaphragm, an external sound board of greater mass than the diaphragm, and a flexible coupling between the two adapted to permit the central (haphragm to respond to relatively high frequencies and adapted to transmit the relatively low frequencies to the sound board, the combined area of the diaphragm and the sound board being suflicient to impart directly to the surrounding air sound waves of clear audibility.

2. A loud speaker comprising a central conical diaphragm, an external sound board of greater mass than the diaphragm, and a flexible coupling between the two adapted to permit the conical diaphragm to respond to relatively high frequencies and adapted to transmit the relatively low frequencies to the sound board, the combined area of the. conical diaphragm and the sound board being sufficient to impart directly to the surrounding air sound waves of clear audibility.

3. A loud speaker comprising a central conical diaphragm, an external sound board and a connection between the conical diaphragm and the sound board adapted to permit the central diaphragm to respond to relatively high frequencies and adapted to transmit the relatively low frequencies to the sound board, the combined area of the conical diaphragm and the sound board being sufficient to impart directly to the surrounding air sound waves of clear audibility.

4. A loud speaker comprising a central conical diaphragm, a wooden sound board providing an annular flange extending radially beyond the conical diaphragm and a connection between the conical diaphragm and the wooden sound board adapted to permit the conical diaphragm to respond to relatively high frequencies and adapted to transmit the relatively low frequencies to the wooden sound board, the combined area of the conical diaphragm and the sound board being sufficient to impart directly to the surrounding air sound waves of clear audibility.

A loud speaker comprising a central conical diaphragm having an integral forwardly flaring brim portion, and a wooden sound board providing a flange portion extending radially beyond the conical diaphragm, said forwardly flaring brim pordiaphragm, said hinge portion bein secured 1 to said sound board, and having exibility sufficient to permit the conical diaphragm to respond to relatively high frequencies and having rigidity suflicient to cause transmission of therelatively low frequencies to the sound board, the combined area of the conical diaphragm and the sound board being suflicient to impart directly to the surrounding I air sound waves of clear audibility.

7. A loud speaker comprisin a sound board, and a conical diaphragm exibly connccted thereto so thata portion of the sound board extends'radially beyond the conical diaphragm, the flexible connection between the conical diaphragm and the sound board having flexibility sufficient to permit the conical diaphragm to respond to relatively high frequencies and having rigidity sufiicient to cause transmission of the relatively low frequencies to the sound board, the combined area of the conical diaphragm and the sound board being suflicient to impart directly to the waves of clear audi-- rounding air sound b il ity. v

8. A loud speaker comprising a central conical diaphragm made of paper, an external sound board made of wood, and a flexible connection between the two having flexibility sufficient to permit the-conical diaphragm to respond to relatively high frequencies and having a rigidity suificient to cause transmission of the relatively low frequencies to the sound boa-rd, the combined area of the conical diaphragm and the sound board being sufficient to impart directly to .the surrounding air sound waves of clear audibility requiring no sound box or megaphone amplification.

9. A loud speaker comprising a sound board having a central opening, a conical diaphragm mounted in said opening, actuating means for the conical diaphragm and means for supporting said actuating means comprising a support attached to the sound board and spanning the central opening thereof. 10. A loud speaker comprising an annular flat sound board having a circular central opening, a conical diaphragm having a circular periphery, said'conical diaphragm being mounted in said opening, and a flexible coupling between the'conical diaphragm and the sound board having flexibility suflicient to permit the conical diaphragm to respond to relatively high frequencies and having rigidity sutficient to cause transmission of relatively low fre uencies to the sound board. 11. A loud spea er comprising an annular sound board having a central 0 ening the' taperin seat, and a conical diaphragm mounte in said opening said diaphragm having a forwardly flaring frusto-conical vbrim portion secured to the sound board on said ta ering seat. i m 12. lou speaker comfprlsm a flat annular sound board made 0 W00 said sound board at said tapering seat.

13. A loud speaker comprising an annul a sound board having a central 0 ening, a coni cal dia hra m mounted in sai opening, said sound oar being provided with -a tapering seat and the conical diaphragm being provided with a-flexible brim portion secured to the sound board on said tapering seat.

14. A- loud speaker comprising a sound board and a conical diaphragm, the sound' board being provided with a tapering seat and theconical diaphragm being rovided witha bent brim port-ion secured to t e sound board on said tapering seat.

A loud speaker comprisinga-conical diaphragm, a sound board and a connection between the conical diaphragm and the sound board adapted to permit the conical diaphragm to respond to relatively high fre-v uencies and adapted to transmit the relatively low frequencies to the sound board, the combined area of the diaphragm and the sound board being sufficient to impartdirectly to the surrounding air sound waves of clear audibility. Y r

16. In a sound reproducing device, a cone and a sounding board connected thereto, said sounding board being freely and flexibly suspended, and means to set them in vibration. 1

17 In a sound reproducing device, the combination of a cone and a flat sounding board of substantialwidth, said sounding board being freely and flexibly suspended, and electric means for operating said cone and board.

18. A loud speaker comprising'a cone and a plane vibratory un'it freely and flexibly supported, a motor and means for mounting said unit and said'motor operatively together,

19. A loud speaker including a freely suspended soundingboard, a cone extending through said sounding board and fastened thereto, and means for actuating said sound- ;w board and cone.

In testimony whereof I aflix my signature.

MARCUS C. HOPKINS.

edge portion of which'is provi ed with a 

